WPF ComboBox - 更改绑定字段的setter中的选择 - ComboBox选择未更新

I have a ComboBox's SelectedItem property bound to an object's field. It uses TwoWay binding, which works fine in most cases; when it loads up, the dropdown's selection is set from the field's getter, and manually changing the selection calls the field's setter.I have a ComboBox's SelectedItem property bound